Maanpaine

Maanpaine is a term used in geotechnical engineering to describe the lateral pressure that soil exerts on adjacent boundaries, such as retaining walls, basement walls, or underground openings. It encompasses both hydrostatic forces within the soil and frictional resistance at the soil–structure interface, and it is a central consideration in the design of structures that press against or enclose soil.

The concept is typically categorized by boundary movement into active, passive, and at-rest maanpaine. Active earth pressure develops when the boundary moves away from the soil, reducing contact pressure. Passive earth pressure occurs when the boundary moves toward the soil, increasing contact pressure. At-rest earth pressure exists when the soil mass is laterally confined and cannot move.

Theoretical models used to estimate maanpaine include the Rankine and Coulomb approaches. These models relate lateral pressure to soil properties such as friction angle (phi), cohesion (c), and unit weight, as well as wall inclination, backfill conditions, and seepage. Common approximations are Ka = tan^2(45 − phi/2) for active pressure, Kp = tan^2(45 + phi/2) for passive pressure, and K0 ≈ 1 − sin(phi) for at-rest pressure. Real-world applications also consider moisture, drainage, and saturation, which affect effective stress and thus the measured pressure.

Applications of maanpaine theory include designing retaining walls, basement and tunnel walls, and other structures interacting with soil. In practice, engineers combine theoretical models with site measurements from devices such as earth pressure cells and sensors to ensure safe and economical designs. The concept remains a fundamental part of soil mechanics and geotechnical engineering.